There are many small commercial water filtering systems in use throughout the United States and some of these systems provide questionable drinking water to consumers. Many of these small filtering systems exist where the surface and shallow ground water quality tend to be high, such as New England, Pennsylvania, Colorado and the Northwest. The water provided by these systems appears to be acceptable, however, without adequate bacterial and chemical testing the actual water quality is unknown. Recent reports indicate that there has been an increased amount of waterborne disease since 1961 and this trend particularly applies to small water systems. As the population continues to increase, there are fewer and fewer water sources in the United States where the water supplies can be adequately protected from contamination. Moreover, as man continues to populate the water sheds, adequate water treatment is becoming more and more necessary for surface and spring water supplies.
Indigenous animals may also contribute to contamination of water supplies and one specific problem is the occurrence of Giardia cysts. Many animals, particularly beaver and muskrat, serve as a reservoir or carrier of this organism and an increase in Giardia cyst cases has been reported over the past few years. The outbreaks have tended to occur more frequently with consumers of small water systems or where the water is provided to a consumer directly from a clear spring, brook, pond or lake, after being treated with only chlorine, if treated at all. In the case of the Giardia cyst, only excessive chlorination will affect the cyst and normal chlorination is virtually ineffective. Moreover, unlike bacterial exposure, the injestion of a very few Giardia cysts will usually produce a parasitic disease.
The probability of small water system users becoming exposed to this organism is increasing daily. Moreover, the cold water areas of this country are considered to be the most susceptible to this type of contamination and filtration followed by disinfection, such as chlorination, is now considered the primary effective barrier against Giardia cysts. The small water systems have a difficult time meeting acceptable bacterial and turbidity criteria which are required for acceptable disease-free drinking water. Therefore, if the small water treatment systems are to provide safe and potable water, some form of treatment beyond disinfection is required.
Presently there are many methods of treating water to remove bacteria, turbidity, and other contaminates and impurities. Many of these systems are extremely effective in purifying virtually any source of water. However, the associated costs and the required technical know-how are the main limiting factors of the high technology systems, and these factors generally are prohibitively expensive for small water systems.